Apparatus for and method of manufacturing brush seals

ABSTRACT

This invention provides an apparatus for and method of manufacturing a brush seal. The apparatus comprises an annular former 22 having a radially outer 24 and a radially inner 30 portion radially separated from each other by an amount G and held relative to each other by locating means 32, and further includes a travelling wire electro discharge machining device and a guide tube. A brush seal 10 is wound onto the former in the usual manner and the filament material 38 cut in the region of the gap G by the travelling wire 44. The wire is inserted between the filaments by first inserting a tube 52 therebetween and passing the wire 44 therethrough. Machining of the filament material is achieved by traversing the wire around the gap G.

FIELD OF THE INVENTION

This invention relates to an apparatus for, and method of, manufacturingbrush seals. It relates in particular not exclusively, to brush sealsproduced by the winding technique.

Brush seals are already well known per se and are therefore notdescribed in detail herein. Briefly, however, they comprise a pair ofgenerally annular sideplates and a plurality of closely packed metallicbristles. The bristles are sandwiched between the sideplates and extendradially therefrom. The free ends of the bristles act against arelatively rotating component to effect a seal.

DESCRIPTION OF THE RELATED ART

The production of brush seals by winding is already well known and isdescribed in detail in UK Patent No. 2001400B. Briefly, however, theprocess involves winding a filament of wire onto an annular formerhaving two seals sideplates incorporated therein and sandwiching thewire between a second pair of sideplates. Each of the two sideplates oneither side of the former are then integrally joined to the wiresituated therebetween by for example welding or brazing. The otherwisefree ends of the wire are then cut away from the former to allow the twoseals to be separated therefrom. Final finishing of the wire, or ratherbristle, may be achieved by grinding.

One well known method of grinding makes use of a centreless grindingtechnique. This method is time consuming, expensive and lacks accuracy.Further to this, it has been found that the bristle elements bend awayfrom the grinding wheel and make accurate machining difficult.

It is an object of the present invention to reduce and possiblyeliminate the disadvantages of the above mentioned method of manufactureby providing an apparatus for and method of manufacture brush sealswhich makes use of the advantages of electro discharge machining, issimple, accurate and which lends itself to both automation and batchprocessing.

SUMMARY OF THE INVENTION

The apparatus of the invention comprises an annular former havingradially outer and inner portions radially separated from each other bya gap and held relative to each other by locating means, and furtherincludes a travelling wire electro discharge machining device and aguide tube. A brush seal is wound onto the former and the filamentmaterial cut in the region of the gap by the travelling wire. The wireis inserted between the filaments by first inserting a tube therebetweenand passing the wire therethrough. Machining of the filament material isachieved by traversing the wire around the gap.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described by way of example only withreference to the accompanying drawings, in which:

FIG. 1 is a cross sectional view of a brush seal.

FIG. 2 is a general view of a portion of an annular former onto whichthe bristle elements of the brush seal are wound.

FIG. 3 is a cross sectional view of the annular former shown in FIG. 2having bristle elements wound thereon and an ED wire cutting apparatusinserted therein, and

FIG. 4 is a perspective view of part of the cutting apparatus of FIG. 3,taken in the direction of arrow IV.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, a brush seal 10 generally comprises one long andone short annular sideplate 12,14 and a plurality of bristle elements 16which are sandwiched therebetween and which extend generally radiallytherefrom. The bristles shown extend generally radially inwards andtheir free ends 18 act against a rotating component such as for examplea shaft 20 to effect a seal therebetween.

Turning now to FIG. 2, the annular former of the present invention 22comprises a first radially outer portion 24, having a pair of annularsideplates 12 situated in recesses 26,28 provided on either side thereofand a second inner portion 30. The second inner portion 30 is spacedradially from the outer portion 24 by a predetermined amount G, and heldrelative thereto by a plurality of pins 32 which locate in holes 34,36provided in both portions 24,30.

A filament of bristle material 38 is wound onto the annular former 22 inthe conventional manner. It will, however, be appreciated that thefilament 38 will lie over the gap G on both sides of the former 22 asshown in FIG. 3. The outer annular sideplates 14 are then applied to theouter surface of the wound filament adjacent their associated sideplates12. The joining operation is then performed by for example welding thetwo pairs of sideplates 12,14 to each other and the bristle material 38sandwiched therebetween and any surplus material removed by for examplegrinding.

Prior to machining the internal diameter of the brush seal 10, the outer24 and if necessary the inner 30 portions of the former are supported infixtures 40 and 42 respectively. The cutting wire 44 from a travellingwire electro discharge machining apparatus 46 is passed between thelayers of the bristle material 38 in the region of the gap G andconnected for operation to the apparatus 46 via machining heads 48,50respectively. In order to facilitate the passing of the wire 44 throughthe mass of bristle material 38 it may be necessary to employ a tube 52which is inserted between the bristle material prior to passing the wire44 therethrough. Preferably, the tube is provided with a chamfered end54 (best seen in FIG. 4) and a slot 56 along its length L. The chamferedend aids the passage thereof through the bristle material 38, whilst theslot 56 provides an outlet for the wire 44 during machining or allowsthe tube 52 to be removed prior to machining.

The filament material 38 is cut to size by passing a machining currentthrough the cutting wire 44 and moving it in a circle along the gap G.It will be appreciated that the wire will cut through the filamentmaterial as it is so traversed together with any locating pins 32. Itwill be further appreciated that an accurate circular form may bemachined by for example rotating the support means 40,42 and hence theseal 10 about a central axis of rotation R. Once all the filamentmaterial has been cut, the wire 44 may be removed and the two finishedseals separated from the former 22.

It will be appreciated that the effect of the inner portion 30 is tolocate the ends of the filaments of bristle material 38 not sandwichedbetween the sideplates 12,14 (the otherwise free ends) in order tofacilitate the machining operation. It will be further appreciated thatthe above mentioned method of machining may be used on brush seals 10not produced by a winding technique if the otherwise free ends of saidseals 10 are similarly constrained by a locating means and a similar gapG provided between the annular sideplates 12,14 of said seal 10 and saidlocating means. Machining of the bristle elements 18 in the region ofthe gap may be achieved in the same manner as described above.

It will be still further appreciated that both the above describedmethods may be adopted for batch processing by stacking a number ofseals 10 on top of each other such that the gaps G are in line with eachother and by using the same cutting wire 44 to cut through all thebristle filaments 38 in the region of all the gaps in one operation.

I claim:
 1. An apparatus for manufacturing a brush seal of the typewhich comprise a pair of annular sideplates having a plurality offilaments of bristle material sandwiched therebetween and projectingradially therefrom and which is produced by winding onto an annularformer, the apparatus comprising an annular former having a firstradially outer portion having a recess formed on either side thereof toreceive a pair of annular sideplates, and a second inner portion spacedradially from the outer portion by a predetermined amount, thereby todefine a gap, and held relative thereto by locating means there beingfurther provided means for cutting the filament material in the regionof the gap and means comprising a tube for enabling the cutting means tobe passed through the filaments.
 2. An apparatus according to claim 1 inwhich the cutting means comprises a travelling wire electro dischargemachining apparatus having the machining wire inserted through thefilament material in the region of the gap.
 3. An apparatus according toclaim 1 in which the tube is provided with a slot along its length and achamfered end.
 4. An apparatus for manufacturing a brush seal of thetype which comprise a pair of annular sideplates having a plurality offilaments of bristle material sandwiched therebetween and projectingradially therefrom and which is produced by winding onto an annularformer, the apparatus comprising an annular former having a firstradially outer portion having a recessed former on either side thereofto receive a pair of annular sideplates, and a second inner portionspaced radially from the outer portion by a predetermined amount,thereby to define a gap, and held relative thereto by locating meanscomprising a plurality of locating pins which locate in holes providedin the outer and inner portions of the annular former.
 5. A method ofmanufacturing a brush seal of the type which comprises a pair of annularsideplates having a plurality of filaments of bristle materialsandwiched therebetween, and which is produced by winding onto anannular former having a first radially outer portion having a recessformed on either side thereof to receive a pair of annular sideplatesand a second inner portion spaced radially from the outer portion by apredetermined amount, thereby to define a gap, and held relative theretoby locating means, the method including the step of cutting thefilaments of bristle material in the region of the gap, thereby torelease the seal from the former, in which the machining wire of atravelling wire electro discharge machining apparatus is used to cut thefilaments of bristle material and the machining wire is passed throughthe filaments of bristle material by first inserting a tube through saidfilaments and then passing said machining wire through said tube.
 6. Amethod of manufacturing a brush seal of the type which comprises a pairof annular sideplates having a plurality of filaments of bristlematerial sandwiched therebetween, and which is produced by winding ontoan annular former having a first radially outer portion having a recessformed on either side thereof to receive a pair of annular sideplatesand a second inner portion spaced radially from the outer portion by apredetermined amount, thereby to define a gap, and held relative theretoby locating means, the method including the step of cutting thefilaments of bristle material in the region of the gap, thereby torelease the seal from the former, in which the machining wire of atravelling wire electro discharge machining apparatus is used to cut thefilaments of bristle material, and in which the machining wire cutsthrough the filaments of bristle material and the locating means as itis traversed around the gap. .Iadd.
 7. An apparatus for manufacturing abrush seal including a pair of sideplates having a plurality offilaments of bristle material sandwiched therebetween and projectingtherefrom, the apparatus comprising:support means for supporting atleast one pair of sideplates with the filaments projecting radiallytherefrom; and a travelling wire electro discharge machining apparatushaving a machining wire extending through the filaments for cutting thefilaments; and moving means for moving at least one of the support meansand machining wire relative to the other for cutting the filaments..Iaddend. .Iadd.8. The apparatus of claim 7, wherein a plurality ofpairs of sideplates are supported in a stack in the support means, andthe machining wire cuts the filaments in the stack of sideplates..Iaddend. .Iadd.9. The apparatus of claim 7, wherein the sideplates areannular, and one of the support means and the machining wire movescircularly relative to the other. .Iaddend. .Iadd.10. The apparatus ofclaim 7, further comprising locating means for constraining free ends ofthe filaments, and the machining wire is located in a gap between thesideplates and the locating means. .Iaddend. .Iadd.11. The apparatus ofclaim 7, wherein the moving means moves the machining wire relative tothe support means. .Iaddend. .Iadd.12. A method for manufacturing abrush seal including a pair of sideplates having a plurality offilaments of bristle material sandwiched therebetween and projectingtherefrom, the method comprising the steps of: supporting at least onepair of sideplates with the filaments projecting radially therefrom;extending a machining wire of a travelling wire electro dischargemachining apparatus through the filaments; and moving at least one ofthe sideplates and the machining wire of the travelling wire electrodischarge machining apparatus relative to the other to cut thefilaments. .Iaddend. .Iadd.13. The method of claim 12, wherein the stepof supporting includes the step of stacking a plurality of pairs ofsideplates for simultaneously cutting the filaments in the stacks ofsideplates. .Iaddend. .Iadd.14. The method of claim 12, wherein thesideplates are annular and one of the sideplates and the machining wiremoves circularly relative to the other. .Iaddend. .Iadd.15. The methodof claim 12, further comprising the steps of constraining free ends ofthe filaments by a locating mechanism spaced from the sideplates by agap, and locating the machining wire in the gap. .Iaddend. .Iadd.16. Themethod of claim 12, wherein the machining wire is moved. .Iaddend.